Outdoor walls and stairs are often constructed of modular blocks laid in predominantly straight lines joined at right angled corners. Corners are highly visible and modular block systems preferably provide visually appealing corner details that do not rely on the skill of the builder.
To construct wall and stairs to match or complement adjacent pavement blocks or pavers, the applicants have previously created a system that has supporting core blocks faced with an exterior veneer of decorative face blocks mounted on the core blocks, described in international patent application PCT/CA2016/000211 and first published as U.S. Pat. No. 9,453,341. The exposed face blocks have horizontal grooves in a rear surface that is not visible in the finished wall. The core blocks have horizontal supporting ridges on which the face blocks are hung by interlocking the grooves and ridges.
Use of separate face blocks mounted on core blocks has several advantages as more fully described in PCT/CA2016/000211. The use of slip molding ensures dimensional conformity and the finished wall structure assembled from the blocks complies with accurate reproducible dimensional requirements. Core blocks are not visible in the finished structures and can be mass produced from standard concrete mixes at low cost without concern for visual appeal. The unique appearance of the structure is achieved using thinner face blocks to cover the core blocks. Face blocks can be manufactured using the same materials, processes, colours, surface treatments and textures as paving blocks used in the same landscaping project. Standard core blocks can be used for the support structure of a project and manufacturing efficiencies result from high volume mass production, reduced inventory requirements and the low cost materials. A customized visual appearance of the project can be achieved by selecting visible face blocks of various colours, materials, shapes, patterns, textures and surface finishes.
When core blocks are stacked to form an inside corner, the ridges in each course align and provide a continuous support for the face blocks that are hung on the ridges in the inside corner. When core blocks form an outside corner, the system described in PCT/CA2016/000211, and published U.S. Pat. No. 9,453,341 Sep. 27, 2016, uses a plastic plug having an forward head shaped with a short length of supporting ridge. The rearward end of the plug is inserted into molded holes in the core blocks for support. The face blocks in an outside corner are then hung on the heads of the plastic plugs. The grooves in the rear surface of the face blocks interlock with the ridges on the heads of the plastic plugs to support the face blocks on the core blocks.
Forming core blocks is challenging since accurate holes are required into which the plastic plugs fit. After the concrete forms are removed, the blocks can slump slightly because the concrete has not hardened or set. Slump can tend to reduce the hole diameter or hole depth which interferes with insertion of the plug when the concrete has set. The holes also weaken the block structure and increase exposure to air which changes the curing of the concrete blocks and durability. In cold climates, the holes can fill with snow or ice or debris when stored outdoors and insertion of the plugs can be impeded.
There remains a demand for an economical easily constructed structural system, for walls and stairs, for example, that ensures accurate assembly of corners with a reliable and simple method of mounting the face blocks.
Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below.